Electronic excitations and UV luminescence in SrO crystals at 8 K

Reflection and luminescence excitation spectra (5–30 eV) were measured for freshly cleaved SrO at 8 K. An emission band at 4.95 eV is dominant for a SrO crystal excited by photons in the region of fundamental absorption (5.6–30 eV). This emission is tentatively attributed to the radiative decay of self-trapped excitons. The emission at 5.03 eV is assigned to the excitons localized near barium impurity ions and is effectively excited by photons in the energy range 5.35–5.65 eV. The threshold energy of the secondary electron-hole pair creation by hot photoelectrons is estimated to be equal to Eth = 13.5 ± 0.3 eV for SrO at 8 K.